Surgical Stapling Instrument

ABSTRACT

A surgical stapling instrument ( 1 ) comprises a staple fastening assembly ( 4 ) in the distal region of said instrument, the staple fastening assembly ( 4 ) including a cartridge device ( 8 ) which comprises at least one closed row ( 17, 18 ) of staples and defines a wavy distal end surface ( 14 ), and an anvil ( 9 ) which defines a wavy proximal staple forming surface ( 20 ) substantially matching the distal end surface ( 14 ) and which is adapted to cooperate with the cartridge device ( 8 ) for forming the ends of the staples exiting from the cartridge device ( 8 ), wherein the distal end surface ( 14 ) and the staple forming surface ( 20 ) have a globally wavy shape including two opposite peaks ( 21 ) and two opposite valleys ( 22 ) angularly spaced at about 90° from the adjacent peaks ( 21 ) and in that said two-peaks-two-valleys wavy shape is formed by a stepped configuration of said surfaces ( 14, 20 ).

The invention relates to a surgical stapling instrument, which can beused for applying surgical staples or clips to tissue. And particularlythe invention relates to an intraluminal surgical stapling instrumentfor the creation of an anastomosis.

Surgical stapling is known in the art as a quick and efficient way ofjoining and repairing tissue and has become not only an acceptable but apreferred alternative to suturing.

The known intraluminal surgical stapling instruments typically comprisean elongate shaft having a proximal actuating mechanism and a distalstaple fastening assembly mounted to the shaft. The staple fasteningassembly typically comprises a staple cartridge device containing aplurality of staples arranged in a circular closed array. A circularcutting knife having a closed cutting edge is contained within thecartridge device and is positioned such that there is at least oneclosed row of staples on the outside of the cutting edge. The knife canbe advanced in an axial distal direction during operation. A trocarshaft extends distally from the cartridge device and is axially movablewith respect to the latter. An anvil is detachably mounted to the trocarshaft and comprises a staple forming surface facing the distal endsurface of the cartridge device and adapted to form the ends of thestaples pushed by a staple driving device against the anvil. Thedistance between the cartridge end surface and the anvil staple formingface can be varied by an adjustment mechanism mounted to the proximalend of the trocar shaft and configured to move the trocar shaft togetherwith the anvil with respect to the staple cartridge device. Theactuating mechanism typically links the staple driving operation to theknife advancing operation such that the tissue contained between thestaple cartridge device and the anvil is simultaneously stapled and cutwhen the actuating mechanism is triggered by the surgeon.

Generally, in the performance of an intraluminal anastomosis, two piecesof lumen or tubular tissue, e.g. intestinal tissue, are joined togetherby a closed row of staples. In performing the anastomosis with asurgical stapling instrument, the anvil is placed in the proximal end ofthe distal lumen or tissue portion (from a surgeons viewpoint) and thecartridge device is placed in the distal end of the proximal lumen ortissue portion to be joined. The placement of anvil and cartridge devicecan be done by inserting them through entry ports cut into thecorresponding lumen by the surgeon or by inserting them endoscopically,e.g. transanally through the rectum. The lumens or tissue portionsdestined to be joint in anastomosis can be tied to the anvil shaftand/or trocar shaft using a suture or other conventional tyingtechnique. Thereafter, the anvil shaft is attached to the trocar shaftof the staple fastening assembly (cartridge device) and the gap betweenthe cartridge device and the anvil is closed, thereby clamping theproximal and distal tissue portions together in the gap. Upon actuationof the intraluminal stapling device one or more closed rows of staplesare driven out of corresponding staple guide slots of the cartridgedevice. The staples are driven through the distal and proximal tissueportions and formed against an array of staple forming grooves of theanvil, thereby joining the tissue portions and forming a tubularpathway.

Simultaneously, as the staples are applied and formed, the circularknife is advanced distally to cut the excess tissue adjacent to theinner annular row of staples. Then, the tissue edge joined by the closedrow of staples is unclamped by advancing the trocar shaft distally withrespect to the cartridge device to move the anvil away from thecartridge device. The stapling instrument is then withdrawn from theanastomotic site by pulling the anvil proximally through the anastomoticorifice defined by the annularly stapled tissue edges.

Although the use of the known surgical stapling instruments is verybeneficial and greatly facilitates the performance of an anastomosis, itinvolves some problems. Often it is difficult to retract the instrumentfrom the site of the operation, because it is difficult to withdraw theanvil through the anastomotic opening defined by the closed row ofstaples, which is somewhat stiff. Moreover, after the operation, theincidence of clinical stenosis at the site of the anastomosis is notrare.

In order to overcome these known deficiencies, it is proposed in WO01/54594 A1 to arrange the closed row of staples in a wavy shape. Inthis way, the line along which the staples of the closed row arearranged has a greater total length than the projection of this lineonto a plane. Consequently, the length of an anastomosis seam is greaterthan that of an anastomosis performed by means of a conventionalstapling instrument. Because of this increased length, the anastomoticsite can assume a larger diameter and is more flexible, so that theanvil can be easier moved through the anastomotic opening. Additionally,the resulting larger anastomosis lumen will alleviate the incidence ofclinical complications.

Nonetheless the wavy shape of the staple arrangement has some drawbacks.For optimum performance of the stapling instrument, the individualstaples are expelled from the cartridge device in a directionperpendicular to the local slope of the wavy shape, which generally isnot parallel to the longitudinal axis of the instrument, requiring acomplex staple drive device. Moreover, due to the oblique orientation ofthe staple driving direction with respect to the anvil approximationdirection (axial direction of the stapler) the alignment of thestaple-forming grooves at the anvil and the staple guide slots of thecartridge device varies undesirably with any variation of the distancebetween the cartridge device and the anvil, thereby limiting the use ofthe stapler to only one thickness of tissue to be joined in anastomosis.

Moreover, since the length of the wavy stapled seam can be increasedonly by increasing the number of waves along the circular staple lineand by increasing the amplitude (axial extension) of the waves, theapplication of wavy circular staplers encounters some limits linked tothe physiological peculiarities of the body tissue. By increasing thenumber of waves (at a given amplitude) along the staple line thegradient of the inclination or flexure of adjacent tissue portions isincreased to an extent which might lead to tissue trauma or localrupture. On the other hand, using a staple line having only one singlesinusoidal wave, the amplitude of the wave, i.e. the axial distancebetween the valley and the peak of the single wave, needs to be veryhigh in order to obtain the desired increase of the length of thestapled seam. Since some tubular organs of the human and animal body,particularly the intestine, have an unilateral blood supply, ananastomosis with a great longitudinal extension with respect to thelumen might leave some regions of tissue completely isolated from bloodsupply, leading to necrosis.

The object of the invention is to provide a surgical stapling instrumentfor performing an anastomosis, which reconciles the contrastingrequirements of maximizing the length of the stapled seam, minimizingthe tissue trauma and reducing the complexity of the staple drivedevice. A further object of the invention is to provide a surgicalstapling instrument being adaptable to different tissue thicknesses.

These objects are achieved by a surgical stapling instrument having thefeatures of claim 1. Advantageous embodiments and variants of theinvention follow from the dependent claims.

The surgical stapling instrument according to the invention comprises aframe having a body portion and a handle as well as a staple fasteningassembly in the distal region of the instrument. The staple fasteningassembly includes a cartridge device housing at least one closed row ofstaples and defining a wavy distal end surface, and an anvil defining awavy staple forming surface which matches the wavy distal end surface.The anvil is movable relative to the cartridge device and is adapted tocooperate with the cartridge device for forming the ends of the staplesexiting from the cartridge device. A moving device is adapted to movethe anvil relative to the cartridge device. A staple driving device isadapted to drive the staples out of the cartridge device towards theanvil. A knife, which has a closed cutting edge, is contained within thecartridge device and is positioned such that there is at least oneclosed row of staples radially on the outside of the cutting edge. Aknife actuating device is adapted to move the knife towards the anvil.

According to the invention, both the distal end surface and the stapleforming surface have a wavy shape including two opposite peaks and twoopposite valleys angularly spaced at about 90° from the adjacent peaksand have a stepped or otherwise offset configuration in order to createthe two-peaks-two-valleys wavy shape.

The stepped surfaces are composed of a series of lands and risers,wherein the lands are substantially perpendicular to the longitudinalaxis of the staple fastening assembly and the exit openings of thestaple guide slots as well as the staple forming recesses areadvantageously defined in the lands.

The stepped surface configuration “oscillates” about the generallytwo-peaks-two-valleys wavy shape configuration, thereby furtherincreasing the length of the stapled seam with respect to the dimensionsof the stapling device and without substantially increasing the overallaxial extension of the anastomosis along the lumen. Moreover, thestepped configuration and the orientation of all the step landsperpendicular to the longitudinal axis allows to arrange all staplesparallel to the staple drive direction of the staple drive device,thereby reducing the force necessary to penetrate the tissue and clinchthe staples against the staple forming surface of the anvil.

Advantageously, the staples are arranged in the cartridge device along awavy line including two opposite peaks and two opposite valleysangularly spaced at about 90° from the adjacent peaks, wherein the linealong which the staples are arranged is substantially parallel to thecorresponding distal end surface of the cartridge device. Preferably theprojection of the cartridge distal end surface and the staple formingsurface and the projection of the staple line onto a plane perpendicularto the longitudinal axis of the staple fastening assembly are circular.

Hence, the tissue interfaces of the surgical stapling instrument have agreater total extension than comparable planar or smooth wavy tissueinterfaces. The particular shape with two opposite peaks and twoopposite valleys angularly spaced at about 90° from the adjacent peaksconsents to obtain an increased length of the stapled seam compared totraditional circular staplers without unnecessarily increasing thegradient of tissue flexure and the total longitudinal extension of theanastomosis along the lumen, thereby reducing the risk of trauma andtissue rupture. The length of the stapled seam is further increased bythe locally stepped or offset surface configuration of the cartridge endsurface and the staple forming surface which “oscillates” about thetwo-peaks-two-valleys wavy shape. This superimposition of two wavepatterns (the global general wave and the local steps), apart fromincreasing the length of the stapled seam without increasingsubstantially the longitudinal extension of the anastomosis, consentsfurther to align the steps, and hence the direction of the guide slotshousing the staples, parallel to the longitudinal axis of the staplefastening assembly, which in turn allows the use of a simple and sturdystaple drive device.

According to an important aspect of the invention, the axial distancebetween the peaks and the valleys of the distal end surface and themating staple forming surface is preferably less than 20 mm, yetpreferably less than 10 mm. This dimensioning will further reduce therisk of tissue necrosis due to blood supply insufficiency.

In accordance with a further aspect of the invention, the staplefastening assembly is dimensioned in a manner that at least the externalcircumference of the anvil is less or approximately equal to the totallength of the two-peaks-two-valleys stepped surfaces along the stapleline. A very good compromise between the lumen diameter requirement andthe requirement of minimizing tissue tensioning during withdrawal of thestapler from the anastomotic site has been obtained by selecting theratio of the outside circumferential length of the anvil (and preferablyalso that of the staple cartridge device) to the staple line length in arange of 0.95 to 1.02.

Turning again to the general two-peaks-two-valleys wavy shape of thedistal end surface and the staple forming surface, this shape can beobtained by different geometric constructions. A regular sinusoidal wavepattern leads to a gradual change of the gradient of flexure of thetissue along the staple line. A zig-zag shape with smoothed cornersresults in a concentration of the tissue flexure in the regions of theopposite peaks and valleys and in substantially flat intermediateregions between respectively a peak and a valley, in which nosubstantial tissue flexure occurs. Alternatively, the distal end surfacemight be advantageously defined by two planes which intersect along adiameter of the circular staple cartridge device and the staple formingsurface might be advantageously defined by two planes which intersectalong a diameter of the anvil. In this case it is advantageous to roundthe zone of intersection of the two half-planes. This would lead tosubstantially fish-mouth shaped surfaces.

Because of the above described geometry of the tissue clamping surfacesand the staple line of the surgical stapling instrument, the anastomoticsite can assume a larger diameter and is more flexible, so that theanvil can be easily removed through the opening created by the knife,and the surgical stapling instrument can be retracted more easily.Additionally, incidence of clinical complications will be reduced.

Moreover, thanks to the perpendicular orientation of the lands of thesingle steps (which define the exit openings of the staple guide slots)with respect to the longitudinal axis of the staple fastening assembly,the pointed ends of staples exiting from the cartridge device stayaligned to the staple-forming grooves provided at the anvil,irrespective of the actual distance between the anvil and the cartridgedevice or the thickness of the tissue clamped therebetween.

Whereas it is conceivable that the knife has a conventional(cylindrical) basic shape with a circular cutting edge, in a preferredversion of the invention the line defining the cutting edge of the knifehas a generally wavy two-peaks-two-valleys or fish-mouth shape (having acircular projection onto a plane perpendicular to the longitudinal axisof the staple fastening assembly). The cutting edge is preferablydefined by a series of steps “oscillating” about its wavy shape andparallel to the line along which the row or rows of staples arearranged. With such a design, the knife has to be moved only by a veryshort distance in order to completely cut the tissue clamped between thecartridge device and the anvil.

In an advantageous version of the invention, the staple fasteningassembly is detachably mounted in the distal end region of the bodyportion. This enables, e.g., the staple fastening assembly to beexchanged during the surgical operation or to be designed as adisposable part (whereas the frame including a major part of themechanical components is sterilizable and reusable). Moreover, thecartridge device can comprise a removable cartridge containing thestaples, such that, e.g., an empty cartridge can be replaced by a freshone, if required, or the cartridge device can be designed as a re-usablecomponent.

These and other features and advantages of the present invention shallbe made apparent from the accompanying drawings and the descriptionthereof, which illustrate an embodiment of the invention and, togetherwith the general description of the invention given above and thedetailed description of an embodiment given below, serve to explain theprinciples of the present invention.

FIG. 1 is a perspective side view of a surgical stapling instrumentaccording to the invention;

FIG. 2 is an enlarged perspective distal-lateral view of a staplefastening assembly of the stapling instrument in FIG. 1;

FIGS. 3 and 3A are a perspective distal-lateral view and a side view ofa staple driving device of a surgical stapling instrument according toan embodiment of the invention;

FIG. 4 is a perspective distal-lateral view of a staple cartridge deviceof a surgical stapling instrument according to an embodiment of theinvention;

FIGS. 5A and 5B are side views of a staple fastening device of asurgical stapling instrument according to an embodiment of the inventionin a retracted and protracted (staples expelled) configuration;

FIGS. 6A, 6B, 6C and 6D are side views of an approximating and staplingoperation of the present invention;

Turning to the figures, FIG. 1 shows an intraluminal surgical staplinginstrument 1. The stapling instrument 1 comprises a frame having a bodyportion including a curved or straight shaft 2 and a handle 3. A staplefastening assembly 4 is preferably detachably mounted at the distal endof the shaft 2, in order to allow for removal of the staple fasteningassembly from the shaft 2 and for replacement by another one, ifdesired.

An actuator trigger 5 is located in the proximal region of the staplinginstrument 1. It can be swivelled towards handle 3 in order to “fire”the stapling instrument 1, i. e. for operating the staple driving deviceand the knife actuating device of the internal mechanism of the staplinginstrument. A rotatable adjusting knob 6 is provided for axiallyshifting a trocar shaft 7, in order to open or close the staplefastening assembly 4, i. e. in order to move the anvil of the staplinginstrument 1.

The staple fastening assembly 4 includes a cartridge device 8 (whichcomprises, in the embodiment, two closed rows of staples) and an anvil9. The anvil 9 is detachably connectable with a distal end 10 of thetrocar shaft 7 which can be moved relative to the cartridge device 8,i.e. along the longitudinal axis X of the staple fastening assembly 4,in order to adjust the size of the gap between the anvil 9 and thecartridge device 8.

The cartridge device 8 comprises a housing 11 which contains thestaples, a circular knife, as well as components of a moving device(adapted to move the trocar shaft 7 relative to the cartridge device 8),a staple driving device (adapted to drive the staples out of thecartridge device 8 towards the anvil 9), and a knife actuating device(adapted to move the knife towards the anvil 9). A distal end surface 14of the cartridge device 8, i.e. the surface from which the staplesexiting from the cartridge device 8 are expelled towards the anvil 9, isformed in a distal end portion 12 received by the circumferential wallof the housing 11.

As already explained above, the staple fastening assembly 4 can bedetachably mounted on the shaft 2 of the stapling instrument by means ofa coupling portion 13 provided at the proximal end region of thecartridge device 8. The terms “proximal” and “distal” relate to the viewof the surgeon during normal use of the stapling instrument.

FIG. 2 is an enlarged distal lateral view of the staple fasteningassembly 4. The distal end surface 14 of the staple cartridge device 8comprises guide slots 15, 16 which receive the staples (not shown) andfrom which the staples are expelled towards the anvil 9 when thestapling instrument is “fired”. These guide slots 15, 16 are arranged intwo closed rows, thus defining a radially outer closed row 17 of staples(i.e. guide slots 15) and a radially inner closed row 18 of staples(i.e. guide slots 16).

As shown in FIG. 2, the guide slots 15 and hence the correspondingstaples of the outer closed row 17 and the guide slots 16 and thecorresponding staples of the inner closed row 18 are circumferentiallystaggered and preferably partially overlapping.

A staple guide part (hidden in the figures) is located below the distalend portion 12 and defines the guide slots 15 for guiding the staples ofthe outer closed row 17 and the guide slots 16 for guiding the staplesof the inner closed row 18. Each of theses guide slots 15, 16 houses onestaple, the pointed ends of the staple facing the corresponding exitopening in the distal end surface 14. The staple guide part as well asthe distal end portion 12 are preferably made of a medical grade resinby injection moulding and may be manufactured integrally as one singlecomponent.

The circular knife, which is not shown in the figures, is guided (in aconventional manner) at the inner periphery of the distal end portion 12of the cartridge device 8. It is moved in distal direction when thestapling instrument is actuated, as usual with conventional circularstaplers.

The anvil 9 comprises a proximally extending anvil shaft 19 which isconfigured to detachably engage the trocar shaft 7 and align the anvil 9angularly with respect to the cartridge device 8. The anvil furthercomprises a proximally facing annular staple forming surface 20 defininga pair of staple-forming grooves for each staple in order to bend thepointed ends of the staple when it is pushed against the staple-formingsurface 20 upon actuation of the staple drive device. The distal endsurface 14 of the cartridge device and the staple forming surface 20 ofthe anvil constitute opposite tissue interfaces destined to contactdirectly and clamp the tissue in the gap between the cartridge deviceand the anvil.

Generally, the overall design and the mechanical components, drivemechanisms and safety features of the surgical stapling instrument areas in known circular stapling instruments (compare e.g. U.S. Pat. No.5,309,927 and WO 01/54594); the three-dimensional shape of the tissueinterfaces and staple lines and some details of the staple drivingdevice, however, are different, as will be explained in the following.

The distal end surface 14 of the cartridge device and the staple formingsurface 20 of the anvil have a generally wavy shape including twoopposite peaks and two opposite valleys 22 angularly spaced at about90°, wherein this two-peaks-two-valleys wave is obtained by a locallystepped or otherwise offset configuration which “oscillates” about thetwo-peaks-two-valleys wavy shape. Particularly, the stepped distal endsurface 14 is composed of a series of lands 23 and risers 24, whereinthe lands 23 are perpendicular to the longitudinal axis X of the staplefastening assembly 4 and the exit openings of the guide slots 15, 16 aredefined in the lands 23. Analogously, also the staple forming surface 20of the anvil is composed of a series of lands 25 and risers 26, whereinthe lands 25 are perpendicular to the longitudinal axis X of the staplefastening assembly 4 and the staple forming recesses are defined in thelands 25.

In both the distal end surface 14 and the staple forming surface 20, thelands 23, 25 define with the risers 24, 26 an obtuse angle in order toreduce local tissue tensioning during clamping and stapling.

All staple guide slots 15, 16 extend in a substantially normal directionto the corresponding lands 23 and parallel with respect to thelongitudinal axis X.

As a result, all staples housed in the guide slots are in parallelalignment with respect to the staple drive direction of the staple drivedevice (which will be described below) which coincides with thelongitudinal axis X.

In accordance with the preferred embodiment, the staples are arranged inthe cartridge device 8 along a wavy line including two opposite peaksand two opposite valleys angularly spaced at about 90° from the adjacentpeaks, wherein the line along which the staples are arranged issubstantially parallel to the distal end surface 14. In order to limitthe diameter of the staple fastening assembly, the described wavy andstepped shape of the tissue interfaces deviates from a hypotheticalcircular reference shape in a plane perpendicular to the longitudinalaxis X only in a direction normal to that plane, such that theprojection of the distal end surface 14 and the staple forming surface20, as well as the annular lines defined by the outer and inner staplerows 17, 18 onto that plane is circular.

As can be seen from the figures, according to the preferred embodiment,both peaks 21 have the same axial distance from a plane perpendicular tothe longitudinal axis X. Analogously, also both valleys 22 have the samedistance from a plane perpendicular to the longitudinal axis X.Preferably, the two-peaks-two-valleys wavy shape and the superimposedlocally stepped shape of the distal end surface 14 and of the stapleforming surface 20 are symmetrical with respect to a first plane definedby the longitudinal axis X and the two valley points 22 and with respectto a perpendicular second plane defined by the longitudinal axis X andthe two peak points 21. This further reduces the longitudinal extensionof the resulting anastomosis for a given target staple line length. Theaxial distance between the peaks 21 and the valleys 22 should bepreferably less than 20 mm, even more preferably less than 10 mm, inorder to reduce the risk of tissue necrosis due to blood supplyinsufficiency.

Although the foregoing description focused primarily on the geometry ofthe tissue interfaces and of the staple line geometry of the staplinginstrument 1, in a preferred embodiment of the invention, the overalldimensioning of the surgical stapling instrument has been made independence from the above described wavy and stepped geometry, such thatat least the external circumference of the anvil 9 is less orapproximately equal to the total length of the tissue interface alongthe staple line. Best results have been obtained by selecting the ratioof the outside circumferential length of the anvil (and preferably alsothat of the staple cartridge device) to the staple line length in arange of about 0.95 to 1.02.

In stapler geometries different from a stepped double wave shape orstepped fishmouth shape of the present invention, experimentation haslead to the following selection of ratios between the staple line lengthand the external circumferential length of the anvil and, preferably, ofthe entire staple fastening assembly:

-   -   In circular staplers, in which the line defined by the closed        row of staples has a stepped shape, leaving a median plane        perpendicular to the longitudinal axis of the staple fastening        assembly, the staple line has a greater length than the external        circumference of the anvil or the staple fastening assembly and        the ratio of the external circumference of the anvil or the        staple fastening assembly to said staple line length is        preferably in the range between 0.89 and 0.97.    -   In circular staplers, in which the line defined by the closed        row of staples has a wavy shape, leaving a median plane        perpendicular to the longitudinal axis of the staple fastening        assembly, the staple line has a greater length than the external        circumference of the anvil or the staple fastening assembly and        the ratio of the external circumference of the anvil or the        staple fastening assembly to said staple line length is        preferably in the range between 0.95 and 1.02.    -   In circular staplers, in which the line defined by the closed        row of staples has an elliptical shape, leaving a plane inclined        to the longitudinal axis of the staple fastening assembly, the        staple line has a greater length than the external circumference        of the anvil or the staple fastening assembly and the ratio of        the external circumference of the anvil or the staple fastening        assembly to said staple line length is preferably in the range        between 0.93 and 0.99.

In the embodiment, the cutting edge of the knife has approximately thesame geometry of a two-peaks-two-valleys general created by a stepped oroffset local geometry, as described above in relation with the tissueclamping surfaces 14, 20. The shape of the knife follows substantiallythe shape of the line along which the inner closed row of staples isarranged but has a slightly smaller diameter such as to cut along ainner circumference with respect to the inner staple row.

FIG. 3 shows the distal portion 27 of a staple driving device suitablefor the stapling instrument which has been described so far. In theembodiment, this distal portion 27 is an integrally molded sleevestructure. It includes an actuator shaft 28 distally ending at a base 29which is reinforced by means of ribs 30. The proximal end of theactuator shaft 28 is coupled to an actuating rod (not shown) inside theshaft 2 of the stapling instrument 1 when the staple fastening assembly4 is mounted to the distal end of this shaft. When the instrument is“fired”, i.e. when an actuating trigger located at the handle of theinstrument is operated, the actuating rod is moved in distal direction,thus pushing the sleeve structure in distal direction, too.

For each staple, the staple driving device 27 comprises a pusherprotruding in distal direction and parallel to the longitudinal axis Xof the staple fastening assembly 4. The pushers are arranged in tworows, particularly an outer row of pushers 31 for the outer closed row17 of staples and an inner row of pushers 32 for the inner closed row 18of staples. In the assembled state of the staple fastening assembly 4,the outer pushers 31 are guided in the guide slots 15, whereas the innerpushers 32 are guided in the guide slots 16. As shown in FIG. 3, allpushers 31, 32 are parallel to each other and to the longitudinal axis Xand their length is such that their distal end sides, i.e. the pushsurfaces 33 (abutting at the crowns of the corresponding staples) followthe two-peaks-two-valleys wavy shape described above with reference tothe distal end surface 14. The push surfaces 33 are substantiallyperpendicular to the longitudinal axis X, thereby defining altogether astepped or offset geometry “oscillating” about the wavy shape describedabove.

The operation of the stapling instrument 1 is illustrated in FIGS. 6A,6B, 6C and 6D. FIG. 6A shows a situation in which the anvil 9 is alreadyinserted in a distal lumen 34 and the proximal part of the staplefastening assembly 4 is placed inside the proximal lumen 35 to be joinedin anastomosis with the distal lumen 34. The two lumens 34, 35 areattached to both the anvil shaft 19 and the trocar shaft 7,respectively. As seen in FIG. 6B, the anvil 9 is approximated to thetrocar shaft 7 until the trocar shaft end 10 engages the anvil shaft 19.The angular alignment of the anvil with respect to the cartridge deviceis ensured e.g. by recesses formed in the anvil shaft 19 andcorresponding serrations formed in the trocar shaft 7. After connectingthe anvil to the trocar shaft 7, rotation of the adjusting knob 6 willapproximate the anvil 9 and the cartridge device 8, thereby pulling thedistal and proximal lumens 34, 35 towards each other and clamping thembetween the end surface 14 of the cartridge device and thestaple-forming surface 20 of the anvil 9. In this phase, the tissuefollows the shapes of the tissue clamping surfaces 14, 20 of thestapling instrument along the line(s) defined by the closed row(s) ofstaples.

When the instrument is fired, the staples are expelled almostsimultaneously from the end surface of the cartridge device, penetratethe tissue and are clinched at the staple-forming surface of the anvil.Immediately afterwards, the cutting edge of the circular knife cuts thetissue held within the circumference of the staples. After firing, thedistance between the anvil 9 and the cartridge device 8 is increased toan extent sufficient for releasing the anastomosis seam. Because of thecombined wavy and stepped geometry of the end surface 14 of thecartridge device and the staple-forming surface 20 of the anvil, thestapled seam has a greater length than comparable stapled seamsobtainable by means of known circular staplers of the same outerdiameter and at the same time a reduced longitudinal extension.Consequently, retraction of the instrument is easier, the risk of tissuetrauma and of post-operative complications is reduced.

Although a preferred embodiment of the invention has been described indetail, it is not the intention of the applicant to limit the scope ofthe claims to such particular embodiment, but to cover all modificationsand alternative constructions falling within the scope of the invention.

1. A surgical stapling instrument (1) comprising: a frame having a body portion (2) and a handle (3), a staple fastening assembly (4) in the distal region of said instrument, the staple fastening assembly (4) including a cartridge device (8) which comprises at least one closed row (17, 18) of staples and defines a wavy distal end surface (14), and an anvil (9) which defines a wavy proximal staple forming surface (20) substantially matching the distal end surface (14) and which is movable relative to the cartridge device (8) and adapted to cooperate with the cartridge device (8) for forming the ends of the staples exiting from the cartridge device (8), a moving device adapted to move the anvil (9) relative to the cartridge device (8), a staple driving device (27) adapted to drive the staples out of the cartridge device (8) towards the anvil (9), characterized in that said distal end surface (14) and said staple forming surface (20) have a globally wavy shape including two opposite peaks (21) and two opposite valleys (22) angularly spaced at about 90° from the adjacent peaks (21) and in that said two-peaks-two-valleys wavy shape is formed by a stepped configuration of said surfaces (14, 20).
 2. A surgical stapling instrument (1) according to claim 1, wherein the distal end face (14) and the staple forming surface (20) are composed of a series of lands (23;25) and risers (24;26), wherein the lands (23;25) are substantially perpendicular to a longitudinal axis (X) of the staple fastening assembly (4) and exit openings of staple guide slots (15, 16) and staple forming grooves are formed in the lands (23;25).
 3. A surgical stapling instrument (1) according to claim 1 or 2, wherein all staple guide slots (15, 16) and staples housed therein are parallel to a staple drive direction of the staple driving device (27) which coincides with a longitudinal axis (X) of the staple fastening assembly (4).
 4. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the staples are arranged in the cartridge device (8) along a wavy line including two opposite peaks and two opposite valleys angularly spaced at about 90° from the adjacent peaks and wherein the line along which the staples are arranged is substantially parallel to the distal end surface (14) of the cartridge device (8).
 5. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the projections of the distal end surface (14) and the staple forming surface (20) as well as the projection of the staple line onto a plane perpendicular to the longitudinal axis (X) of the staple fastening assembly (4) are circular.
 6. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the maximum axial distance between the peaks (21) and the valleys (22) of the surfaces (14;20) is less than 20 mm, preferably less than 10 mm.
 7. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the external circumference of the anvil (9) is less or approximately equal to the total length of the distal end face (14) along the staple line.
 8. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the ratio of the outside circumferential length of the anvil (9) to the staple line length is comprised in the range from 0.95 to 1.02.
 9. A surgical stapling instrument (1) according to any one of the preceding claims, wherein both opposite peaks (21) have the same axial distance from a plane perpendicular to the longitudinal axis (X) and both opposite valleys (22) have the same axial distance from a plane perpendicular to the longitudinal axis (X).
 10. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the two-peaks-two-valleys stepped shapes of the distal end face (14) and of the staple forming surface (20) are symmetrical with respect to a first plane defined by the longitudinal axis (X) of the staple fastening assembly (4) and the two valley points (22) and with respect to a perpendicular second plane defined by said longitudinal axis (X) and the two peak points (21).
 11. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the staple driving device (27) comprises a plurality of pushers (31, 32) suitable to directly contact the staples and push them distally against the anvil (9), wherein all pushers (31, 32) are parallel to each other and to the longitudinal axis (X) of the staple fastening assembly (4).
 12. A surgical stapling instrument (1) according to the preceding claim, wherein the length of the pushers (31, 32) is such that their distal push surfaces (33) follow the two-peaks-two-valleys wavy shape of the distal end surface (14).
 13. A surgical stapling instrument (1) according to claim 11 or 12, wherein the push surfaces (33) are substantially perpendicular to the longitudinal axis (X).
 14. A surgical stapling instrument (1) according to any of claims 11 to 13, wherein all pushers (31, 32) are integrally formed in a single-piece structure (27).
 15. A surgical stapling instrument (1) according to any one of the preceding claims, comprising: a knife having a closed cutting edge, wherein said knife is arranged in the cartridge device (8) and positioned such that there is at least one closed row (18) of staples on the outside of the cutting edge; a knife actuating device (27) adapted to move the knife distally towards the anvil (9), wherein the line defining the cutting edge of the knife has a globally wavy shape including two opposite peaks and two opposite valleys angularly spaced at about 90° from the adjacent peaks and in that said two-peaks-two-valleys wavy shape is obtained by a locally stepped configuration of the cutting edge.
 16. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the cartridge device (8) houses at least two closed rows (17, 18) of staples, wherein the staples of adjacent rows (17, 18) are staggered with respect to each other and wherein the step lands (23) defining the exit slots of the two rows are staggered with respect to each other.
 17. A surgical stapling instrument (1) according to any one of the preceding claims, wherein the staple fastening assembly (4) is detachably mounted in the distal end region of the body portion (2).
 18. A stapling instrument (1) according to any one of the preceding claims, wherein the cartridge device (8) comprises a removable cartridge containing the staples.
 19. Staple fastening assembly, characterized by the features of the staple fastening assembly (4) as defined in any of claims 1 to
 18. 20. Cartridge device, characterized by the features of the cartridge device (8) as defined in as defined in any of claims 1 to
 18. 21. Knife, characterized by the features of the knife as defined in claim
 15. 